The 765 miles of pipeline, now under construction, has come under fire from the United States and several eastern European, Nordic and Baltic Sea countries which fear it will increase the European Union's reliance on Russian gas.
Venezuela output fall and Iran sanctions tightening market.
Delays are an attempt to force Russia to the negotiating table with Ukraine on gas transit.
Departure leaves open the question of whether the project can succeed without the company’s technology.
Russia undertook to cut its production by 228,000 bbl/d but has struggled to comply with the pact.
One of the key Russian officials to foster a supply pact with OPEC, Kirill Dmitriev, signaled on April 8 Russia wanted to raise oil output when it meets with OPEC in June because of improving market conditions and falling stockpiles.
Sources told Reuters that Saudi Arabia is having a hard time convincing Russia to stay much longer in the OPEC-led pact, and Moscow may only agree to a three-month extension.
Request could delay the Russian project to pump natural gas to Europe.
Russian-led company expects to complete pipeline by the end of 2019.
Comments from executive contrast with company’s previous statements.
